Stop motion for knitting machines



June 21, 1960 P. J. SCHOENSTER EI'AL STOP MOTION FOR KNITTING MACHINES 3 Sheets-Sheet 1 Filed July 18, 1955 FIG. 2 H63 I /0 F LAP COMPLETED YARN POSITIONING ACTIVE LAP INACTIVE LAP PRESS OPERATION FIG.5

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STOP MOTION FOR KNITTING MACHINES Filed July 18. 1955 3 Sheets-Sheet 2 INVEN TORS June 21, 1960 P. J. SCHOENSTER ETAL STOP MOTION FOR KNITTING MACHINES 3 Sheets-Sheet 3 Filed July {L8, 1955 STOP MOTION FOR KNITTING MACHINES Peter J. Schoenster, Teaneck, and Max E. Ebert, Ridgefield, N.J., assignors to Alfred Hofmann & (20., West New York, N..l., a corporation of New Jersey Filed July 18, 1955, Ser. No. 522,694

2 Claims. (Cl. 66-163) This invention relates to stop motion mechanisms for knitting machines and more specifically, for such devices particularly applicable to flat knitting machines such as the tricot machines.

Numerous stop motion mechanisms, applicable in the textile field for use in warping and knitting operations, have been proposed and used with more or less satisfactory results.

In the case of warp forming equipment and circular knitting machines, it has been possible to utilize stop motion controls of a type well known in the art, which consists substantially of using the tension of the individual yarn strands to prevent a light, metallic lever of good electrical conductivity, from closing an electrical control circuit. Accordingly, when the yarn tension is eliminated, as when the yarn breaks, said levers, connected to one side of said circuit, will either drop or lift to make contact with the other side of said circuit. This action and the use of interposed magnetic relays connected in the main circuit for energizing the operating motor, is effective to open a switch and deenergize said motor to stop the machine, in the event of yarn failure.

The thus described stop motion device is satisfactory and effective where a relatively small quantity of individual yarn strands are used and where available space permits the installation of the necessary equipment.

In flat knitting machines, such as the tricot machine, the flow of adjacent yarn strands is usually at the rate of from 22 to 32 individual yarns per inch, however, in many of the finer gauge machines being manufactured and now available, 40 or more yarns per inch are drawn off from a yarn beam practically in the form of a yarn sheet. In such knitting machines, the lever type of stop motion is entirely impracticable for the following reasons:

(1) Space limitations make it impossible, even with staggered arrangements, to set up such individual yarn strand controls for stop motion purposes.

(2) It is impractical to thread each yarn strand through this type of device, and re-thread broken strands, during the course of the knitting operations, without a prohibitive amount of lost time. Accordingly, attempts to use this type of stop motion device have been fruitless and discarded.

Other known types of stop motion controls rely on defects in the fabric to actuate means for stopping the machine, as by means of a photoelectric eye or scanner, detailed in recently issued patents. Such devices necessitate that the scanner be reciprocated back and forth over the freshly knitted fabric along the width of the machine. When a defect occurs in the fabric, the variation in light density at the point of defect is sensed by the scanner when-the same reaches the defect and is effective to make an electrical circuit operative and to thus stop the machine. The photoelectric eye or scanner type of stop motion device has been widely accepted as the most practical form of such device known to' the art, despite the following short-comings:

2,941,388 Patented June '21.,

(1) The path of the scanner cannot extend sutficiently close to the knitting elements to provide a sufficiently instantaneous actuation of the stop motion device upon a breakage of the yarn strand or other yarn defect.

(2) At the time the scanner becomes operative and actuates the stop motion, certain types of knitting defects will already have occurred which may give rise to additional serious damage, not only to the knitted fabric but also to the knitting elements as well.

(3) The photoelectric eye type of stop motion control is costly and cumbersome, and interferes with ready access to the machine during the knitting operations and when knitting adjustments must be made.

(4) The scanner type of stop'motion mechanism has a limited range of optimum functioning in terms of the speed of machine operation, and with the very high speed machines recently introduced which have speeds upwards to 1,000 c.p.m., the reciprocation of the scanner in its travel back and forth overthe width of the machine would have to be accelerated to an extent such that the device could not function properly and would not be able to cope with the fabric production speeds of such high speed machines.

Accordingly, an object of this invention is to provide an improved method and means for controlling the operation of a stop motion device wherein the breaking of a yarn end will cause instantaneous operation of the control means and thus accelerate the response of the stop motion device to such yarn breakage.

Another object of this invention is to provide improved control means for a stop motion device wherein such control means is disposed relative to the knitting elements so as to be instantaneously responsive to variations in the operations of such knitting elements caused by knitting defects such as yarn breakage and the like.

A further object of this invention is to provide an improved device of the character described, which is of simple construction, is compact and does not detract from the normal accessibility to the machine, and which is efficient at very high machine speeds as well as at lower speeds.

Yet another object of this invention is to provide a device as described, which is associated with the knitting elements, such as the sinker units of the machine, such units being modified to incorporate an element of said device.

Still another object of this invention is to provide an improved method of actuating a stop motion means and involving the combined action of two basic knitting elements such as the motion of the sinkers and needles relative to each other.

Still a further object of this invention is to provide control means for a stop motion including standard knitting needles of a flat knitting machine and conductive elements disposed adjacent said needles for contact by said needles in response to a variance in deflection of the needles, caused by yarn breakage or needle loading, thereby providing circuit means for instantaneous operation of the stop motion.

Essentially, the control means embodying the invention comprises a conductive element disposed adjacent the usual spring beard needles of a knitting machine, such element being conveniently related to the sinkers by either being directly mounted on the sinkers in sections connected with each other, or in single units; or mounted on separate mounting means disposed adjacent the sinkers, preferably, the mounting means being adjustable to vary the position of the element relative to the sinkers or the needles of the machine; or, connected with the existing motions of the sinker or the needle bar of the machine, however, the element may be independently actuated.

Other objects of this invention will in part be obvious and in part hereinafter pointed out.

In the drawing, Fig. 1 to Fig. 8 are schematic showings of the several knitting elements of a knitting machine including sinkers, needles, yarn guides and presser bar, in successive positions of significance during the course of a knitting cycle during the operation of a conventional knitting machine.

Fig. 9 is a side elevational view of a sinker assembly including the novel stop motion control element embodying the invention;

Fig. 10 is a view similar to that of Fig. 9, showing a modified form of the invention,

Fig. 11 is a perspective viewof an individual sinker unit, showing the disposition of the control element;

' Fig. 12 is a side elevational view showing still another form of the invention;

Fig. 13' is a view similar to thatof Fig. 12 and showing a modification thereof; 1

1 Fig. 14 is a view similar. to that of Figs. 9, 10, showing a modification thereofj Fig. 15 is a view similar to that of Figs. 9, 1 showing another modification thereof; I i

Fig. 16 is a circuit diagram showing the connections between the knitting elements forming sensing means for yarn failures and knitting defects, and the circuit including the stop motion of the knitting machine; and

Fig. 17 is a schematic showing of photoelectric means for relaying a signal derived from the sensing elements embodying the invention, to actuate the stop motion of the knitting machine; and

Fig. 18 is a side elevational view of still another form of the invention.

T o more readily understand the significance and scope of the instant invention, in respect to both the method and apparatus involved, it will be desirable to review the conventional knitting cycle of a straight knitting machine of the spring beard needle type, as indicated in Figs. 1-8, illustrating the successive, interrelated positions of the sinkers It the spring bear needles 11, yarn guides 22, 13 and presser bar 14 in relation to yarn 15.

Thus, as shown in Fig. l, the knitting elements are in their so-called inactive lapping position and the guides 12, 13 areabout to move in the direction indicated by the arrow in Fig. l, and reaclrwhatmay be termed the active lapping position shown in Fig. 2. At this point, the guides 22, 13 move laterally preparatory to completing the lapping as shown in Fig. 3.- i I Fig. 4 shows the needle 11 after rising for the yarn positioning on the upper section of the shank of the needle, the needle rise being indicated by the distance x. Thereafter, as shown in Fig. 5, the presser bar 1 moves forwardly toward the heard of needle 11, while the sinker retracts and the needle 11 moves downwardly to permit the yarns 15, now under the head of the beard,

to be pulled through the previously formed loop of the fabric knitted which is held for knocking over as shown in Fig. 6. Thereafter, the sinking operation takes place as shown in Fig. 7, during which the needle 11 makes a gradual upward movement, indicated in dotted lines, while the sinker it moves forwardly as indicated by the arrow.

It is noted that the degree or" the forward motion of the sinker it in relation to the position of the needle 11, at this point and the relative positions thereof indicated in Fig. 8, is of critical significance in connection with the instant invention. Thus, the distance between the throat of the sinker 1i) and the needle 11 is a significant factor in establishing the rypeof. fabric to be kn we d. Therefore. it is customary practice when knitting tight fabrics to adjust the distance between the sinker throat and the up and down path of the needle by reducing the same. Contra, when knitting looser fabrics, =i.e., with longer yarn supplied for each knitting cycle, it is customary to provide more sinkerfso. that the yielded yarn is retained.-

for the formation of the loop in the specified requirements for the given types of fabrics.

It is also important to note that with the position of the knitting elements indicated in Figs. '7, 8, when sinker 10 has moved in the direction of the arrow to its extreme forward adjusted position, the needles 111 are subject to deflection from their positions indicated in dotted lines, by reason of the confinement of the shanks of the needles inside the last formed loop held in the throat of the sinkers 10. Such deflection is aided by the pull of the fabric F in the direction of arrow X, shown in Fig. 8.

Accordingly, the deflected positions of the needles during the knitting cycle has an important bearing on the instant invention, inasmuch as the yarn is effective to cause indicated deflection of the needle shanks only so long as it remains unbroken or other knitting defects are avoided. However, in the event of yarn failure, breakage or other knitting defects, the needle shanks will relax to their normal straightness and condition. Such deviations from normal needle deflection phenomena are utilized to operate a stop motion mechanism associated with the knitting machine, as hereinafter described.

Thus, as shown in Fig. 9, the sinker units 16 are cut out as at 17 to receive an electrically conductive strip 18 suitably fixed to an insulating strip 19 and thus insulated from the conductive portions of unit 16. The strip 19 is suitably mounted in cut out 17 and spacer strips 20 may be used to adjust the position of the forward edge of strip 18 relative to needles 11. Alternatively, spacer strip 20 may be omitted and insulating strip 19 may be formed with slots to allow the strip wand conductive strip 13 afiixed thereto, to be moved to adjusted positions and fixed in such positions by screws passing through said slots.

As shown in Fig. 9, when needles 11' are in their usual deflected positions during the knitting cycle as determined by the last loop formed, they are slightly spaced from the forward edge of conductive strip 18. However, in the event of yarn failure or other knitting defect, the specific needle 11 involved will relax to the position indicated in dotted lines, to make electrical contact with conductive strip 18. Such contact is effective to close an electrical circuit for operating the stop motion means as hereinafter described in detail. i

In Fig. 10, where sinker unit 1611 is formed of electrical insulating material, the conductive strip 18:: may be mounted directly in cutout portion, spaced strips 20 or slots in strip 1812 being used to adjust the position of strip 18a, as previously described, so as to make contact with needles 11 in the event of yarn breakage or the like.

As shown in Fig. 11, the conductive strip 18;: extends across a single sinker unit 16a formed of electrical insulating material, providing contact means from one sinker to another. Alternatively, Said strip may be mounted independently of the sinker unit across the entire knitting machine, or in sections across any number of sinkers.

In Fig. 12, the conductive strip 18 is attached to insulating strip 19 which is fixed to a thin plate 21 mounted on a lever member 22 which may have independent lateral motions. Strips 18, 19 are located in cutout'portion 17a of the sinker unit, adjacent the underside of presser edge 14 and presser bar 14a.

In Fig. 13 is shown an arrangement similar to that of Fig. 12, except that plate 21 is fixed to a bracket 23 which is pivoted at 23a on sinker bar 24. Screws 25 provided with lock nuts, fix bracket 23 in selected positions to adjust the position of strip 18 relative to the throat of the sinkers 10; As shown in Fig. 14, the strip 18 may be located on the underside of sinker 10, rather then on the upper portions thereof, as previously shown.

In Fig. 15, the arrangement is similar to that of Fig. 14, except that a second conductive strip 28 fixedonan insulating strip 29, is mounted on the fore portion of sinker 10 so as to be located forwardly of the needle '11. Thus, with certain knitting failures, such as the socalled loading of the needles, wherein the needles 11 are pulled forwardly in the direction of the flow of knitted fabric F, the loaded needles will be deflected and contact strip 28.

It will be apparent that there is provided, as shown in Fig. 15, an arrangement of conductive elements operative to close an electrical circuit for actuating a stop motion means, in the event of yarn failure, wherein the needles 11 move rearwardly to their normal, non-stressed position to make contact with strip 18; and in case of needle loading, said needles will be moved forwardly as indicated by the dotted line position thereof, to make contact with strip 28 and again actuate the stop motion means.

The circuit connections between the knitting elements described above, and the stop motion means, is shown in Fig. 16. The conductive strip 18 on sinker bar 16 forms one side of an electrical circuit energized from the secondary winding S of a step-down transformer T, with a rectifier R interposed. The needle bar 11a, carrying needles 11, forms the other side of said circuit, providing an input to an amplifier A. The output of amplifier A is supplied to a relay 30 which controls the motor circuit energizing the motor operating the knitting machine.

It will be apparent, that upon breakage of yarn 15 or the incidence of other knitting defects such as needle loading which is caused by failure of the presser edge 14 to close the beard of the needle 11 or pin holes caused by improper lapping of the yarn, the needles 11 will assume positions contacting the conductive strips, thereby closing the indicated circuit to open the motor circuit. Such action will be instantaneous and the machine op erating motor will be stopped without delay.

As shown in Fig. 17, the electrical pulses incident to the short circuiting of needle bar 11a and strip 18, may be registered on a galvanometer or ammeter 31 Whose pointer 32 normally is in interposed relation between a light source, not shown, and a photoelectric cell 33 whose output is connected to the input of amplifier A. An abnormal movement or deflection of any needle 11, caused by yarn failure, needle loading or the like, will result in a contact with the conductive strip, as described, and the resultant current registering on galvanometer 31 will cause movement of pointer 32 thereof and a resultant pulse from cell 33 which is amplified to actuate relay 30.

The low voltage operation of the control circuit through step-down transformer T is effective to avoid burning or arcing when needles 11 contact strip 18. A reset switch, not shown, may be used to restore relay 30 to its normal operative position, preparatory to starting the knitting machine after the yarn failure or knitting defect has been corrected.

As shown in Fig. 18, the combination of conductive strip 18 and insulating strip 19 may be mounted on a bracket 34 which is secured to a fixed shaft 35 on the knitting machine, such as the needle bar shaft or the like. The strips may be slotted to allow the use of mounting screws, not shown, thereby permitting adjustment of the strip 18 relative to the needles L1 to permit contact, as indicated in dotted lines, in the event of yarn breakage. Such contact is operative to actuate the stop motion means, as previously described.

It will thus be seen that there has been provided improved means for actuating a stop motion means in a fiat knitting machine, as well as an improved method of actuating such stop motion, to accelerate the stoppage of the machine in response to yarn failures or other knitting defects.

Since various changes might be made in the several embodiments of the invention described herein without departing from the spirit of the invention, it is understood that all matter herein shown or described shall be deemed illustrative and not by way of limitation except as set forth in the appended claims.

Having thus disclosed our invention, we claim as new and desire to protect by Letters Patent:

1. The method of knitting yarns on a straight knitting machine having an electrically operated stop motion associated therewith and a control circuit for said stop motion including spring beard needles on said machine and an elongated electrically conductive member located adjacent said needles, comprising operating said machine to form normally tensioned yarn loops about said needles during the knitting cycle thereby tflexing the shanks of said needles into positions spacing said needles from said conductive member, and closing said control circuit in response to the absence of a normally tensioned yarn loop on at least one of said needles whereby the upper portion of said needle moves to contact said conductive member, thereby operating said stop motion.

2. The method of knitting yarns on a straight, spring beard needle machine having an electrically operated stop motion and a control circuit therefor including spring beard needles and contact means adjacent said needles, comprising operating the machine to form normally tensioned yarn loops on the needles and thereby normally flexing the needle shanks to space said needles from said contact means, and closing said circuit in response to deviations in the normal flexure of the shank of at least one needle whereby the upper portion of said needle moves to engage said contact means and to thereby operate said stop motion.

References Cited in the file of this patent UNITED STATES PATENTS 2,036,093 Page Mar. 31, 1936 2,648,962 Schwanda Aug. 18, 1953 2,669,106 Pei-nick Feb. 16, 1954 2,696,722 Shepard Dec. 14, 1954 2,711,093 Edelman et a1. June 21, 1955 FOREIGN PATENTS 487,615 Germany Dec. 10, 1929 

